Selective call receivers (including pagers) have historically relied on batteries as their main power source. As selective call receivers become smaller, the battery occupies an increasing amount of space relative to the remainder of the selective call receiver's housing. Therefore, it is desirable to reduce the size of the battery while maintaining at least the same energy capacity as contemporary batteries. Air-breathing (e.g., zinc-air) batteries meet these requirements, and therefore, are becoming more widely used in selective call receivers. As is known, proper zinc-air battery operation relies on air availability since the internal chemical reaction that occurs in a zinc-air battery results from the oxygen-zinc reaction.
Contemporary zinc-air battery construction incorporates the zinc into a casing having a number of holes to allow air to reach the zinc. These holes are initially sealed to prevent the zinc from prematurely reacting with the air (which reduces the battery's shelf life). Before using the battery to power a product, the seal(s) covering the air-holes are removed so as to allow the infiltration of air.
Generally, battery manufacturers attempt to produce batteries that will meet the broadest market demand. Therefore, it is common to manufacture batteries with a larger amount (or size) of holes than necessary to meet the needs of many applications. Regrettably, this practice tends to result in premature fuel exhaustion (commonly referred to as "self discharge"). That is, since the zinc-air reaction is dependent upon the amount of oxygen allowed to reach the zinc, the resulting continuous chemical reaction is often in excess of the requirements of the device due to the excessive number of holes, and therefore, the amount of air supplied. Thus, a need exists for an air-breathing battery in which the chemical reaction may be selectively controlled depending on the power requirements of the device being operated.